1. Field of the Invention
The present general inventive concept generally relates to a developing apparatus that includes a developing unit and a photosensitive unit. More particularly, the present general inventive concept relates to a developing apparatus that includes a pushing unit that can allow a developing member of a developing unit to be in contact with or to be spaced apart from an image carrier of a photosensitive unit, and an image forming apparatus having the same.
2. Description of the Related Art
Generally, since the lifetime of a photosensitive drum is shorter than the lifetime of a developing roller, if a photosensitive unit that includes a photosensitive drum and a developing unit that includes a developing roller are configured as a single unit, the developing unit, which has a longer life, may be discarded along with the photosensitive unit, which is wasteful. Also, in recent years, in order to reduce the size of an image forming apparatus, there has been a trend to use a structure in which the developing unit and the photosensitive unit can be separated from each other.
In a case in which the developing unit and the photosensitive unit can be separated from each other, there is a need for a structure that allows the developing roller of the developing unit to be selectively spaced apart from the photosensitive drum of the photosensitive unit.
FIGS. 1 and 2 illustrate a conventional developing apparatus 1. FIG. 1 illustrates a state in which a developing unit 2 is spaced apart from a photosensitive unit 3, and FIG. 2 illustrates a state in which the developing unit 2 is in contact with the photosensitive unit 3.
The developing unit 2 includes a developing housing 2-1 and a developing roller 4 disposed in an upper portion of the developing housing 2-1. The photosensitive unit 3 includes a photosensitive housing 3-1 and a photosensitive drum 5 disposed in an upper portion of the photosensitive housing 3-1. The developing unit 2 and the photosensitive unit 3 are connected by a hinge 9. Accordingly, the developing unit 2 and the photosensitive unit 3 can be rotated a predetermined angle on a shaft of the hinge 9.
A pushing lever 6 is disposed to be rotated a predetermined angle below the photosensitive unit 3, and a pressed portion 7, to be pressed by a front end of the pushing lever 6, is provided on a lower portion of the developing unit 2.
Accordingly, if the front end of the pushing lever 6 of the photosensitive unit 3 is inserted into the pressed portion 7 of the developing unit 2 by rotating the pushing lever 6, as illustrated in FIG. 1, a predetermined angle in a clockwise direction, the lower portion of the developing unit 2 receives a force in the left direction so that the developing unit 2 is rotated in the clockwise direction on the shaft of the hinge 9. Then, as illustrated in FIG. 2, the developing roller 4 of the developing unit 2 is in contact with the photosensitive drum 5 of the photosensitive unit 3 so that the developing unit 2 and the photosensitive unit 3 are in a state in which they are in contact. When the pushing lever 6 is rotated a predetermined angle in the counterclockwise direction from this state, the front end of the pushing lever 6 is removed from the pressed portion 7 so that the developing unit 2 is rotated in the counterclockwise direction on the shaft of the hinge 9. Then, the developing roller 4 of the developing unit 2 is spaced apart from the photosensitive drum 5 of the photosensitive unit 3 so that the developing unit 2 and the photosensitive unit 3 are in a state in which they are spaced apart.
As illustrated in FIGS. 1 and 2, the structure, in which the developing unit 2 is rotated a predetermined angle by using the pushing lever 6 so that the developing unit 2 is in contact with or spaced apart from the photosensitive unit 3, cannot operate smoothly because the operation of the pushing lever 6 to push the developing unit 2 depends on the mechanical configuration of the pushing lever 6 and the pressed portion 7 and because the direction of the force to rotate the pushing lever 6 is not matched with the direction of the force to push the developing unit 2. Specifically, a substantial amount of force is needed at the time when the pushing lever 6 goes over a projection 7a of the pressed portion 7.
Accordingly, there is a need for a developing apparatus that has a pushing structure that can smoothly push a developing unit, slowly increase force, and match a pushing direction of the developing unit with a pushing direction of a pushing lever.